Conventionally, in the manufacture of semiconductor devices, micro-processing by lithography using a photoresist composition has been carried out. The micro-processing is a processing method comprising forming a thin film of a photoresist composition on a silicon wafer, irradiating actinic rays such as ultraviolet rays through a mask pattern on which a pattern for a semiconductor device is depicted, developing it to obtain a resist pattern, and etching the substrate using the resist pattern as a protective film. However, in recent progress in high integration of semiconductor devices, there has been a tendency that shorter wavelength actinic rays are being used, i.e., ArF excimer laser beam (wavelength 193 nm) has been taking the place of i-line (wavelength 365 nm) or KrF excimer laser beam (wavelength 248 nm). Along with this change, influences of random reflection and standing wave of actinic rays from a substrate have become serious problems. Accordingly, it has been widely studied to provide an anti-reflective coating between the photoresist and the substrate (bottom anti-reflective coating).
As the anti-reflective coatings, inorganic anti-reflective coatings made of titanium, titanium dioxide, titanium nitride, chromium oxide, carbon or α-silicon, etc. and organic anti-reflective coatings made of a light absorbing substance and a high molecular weight compound are known. The former requires an installation such as a vacuum deposition apparatus, a CVD apparatus or a sputtering apparatus, etc. In contrast, the latter is considered advantageous in that it requires no special installation so that many studies have been made. For example, mention may be made of the acrylic resin type anti-reflective coating having a hydroxyl group being a crosslink-forming substituent and a light absorbing group in the same molecule as disclosed in U.S. Pat. No. 5,919,599 and the novolak resin type anti-reflective coating having a hydroxyl group being a crosslink-forming substituent and a light absorbing group in the same molecule as disclosed in U.S. Pat. No. 5,693,691.
The physical properties desired for organic anti-reflective coating include high absorbance to light and radioactive rays, no intermixing with the photoresist layer (being insoluble in photoresist solvents), no diffusion of low molecular substances from the anti-reflective coating material into the topcoat photoresist upon application or baking under heating, and a higher dry etching rate than the photoresist.
In recent years, miniaturization of process size in a lithography process by use of KrF excimer laser beam or ArF excimer laser beam, that is, miniaturization of formed photoresist pattern size is advanced. In order to prevent collapse or the like of photoresist pattern that is accompanied with miniaturization of photoresist pattern, it is desired to make the photoresist thinner. In addition, when the photoresist is used in a form of thin film, in order to inhibit decrease in film thickness of photoresist layer in the process of removing organic anti-reflective coating used together by etching, it is desired that the organic anti-reflective coating can be removed by etching for a shorter time. That is, in order to make the time required for an etching removing step shorter, there are demands for organic anti-reflective coatings that can be used in a form of thinner film compared with the conventional ones, or organic anti-reflective coatings having a higher selection ratio of etching rate between the organic anti-reflective coating and photoresist.
In addition, in a lithography process by use of ArF excimer laser beam (wavelength 193 nm), recently pattern collapse has become a problem with miniaturization of photoresist pattern. It is thought towards this problem that pattern collapse is prevented by making photoresists thinner and thus lowering the aspect ratio. However, there is fear that making photoresists that acts as a mask in etching process of semiconductor substrate thinner would cause any problems in substrate processing by etching.
Therefore, it is considered for solving these problems to apply a process in which a layer of inorganic material that is called a hard mask is used as an etching stopper. As the hard mask, materials having absorption in a light of wavelength 193 nm, such as silicon oxide nitride (SION) or silicon nitride (SiN) are used in many cases. Thus, it is considered that an anti-reflective coating used together with such a hard mask is required to have a small attenuation coefficient (k) compared with the existing anti-reflective coatings that are not used together with a hard mask. For example, in case where an anti-reflective coating having a film thickness of 20 to 50 nm formed on a hard mask of silicon oxide nitride (SiON) or silicon nitride (SiN) is used, it is presumed that an attenuation coefficient (k) of the anti-reflective coating at light of a wavelength 193 nm is suitably about 0.1 to 0.3 (for example, see Non-patent Document 1).
From the above-mentioned circumstances, it has been desired to develop novel anti-reflective coatings.
On the other hand, it is disclosed to use polyesters synthesized from 1,3,5-tris(2-hydroxyethyl) cyanuric acid as an anti-reflective coating (for example, see Patent Documents 1 and 2).    Patent Document 1: EP-A-1298492 (2003) specification    Patent Document 2: EP-A-1298493 (2003) specification    Non-patent Document 1: Proceeding of SPIE, US, Vol. 5039, 2003, pp. 940-947